Hi K, I was fortunate enough to get my Escher for just a tenner but it had small chip on the inside rim. Very difficult to find though! But I have seen them going quite cheap recently (not the Physco ones though!)
Incidentally, the official name for the Escher is actually Carré
— sorry not shouting but just so you can see the accented 'e' properly
Apparently they never sold well, hence the reason they're now so collectable.